For certain applications, such as Inertial Confinement Fusion (ICF), it is desirable to utilize laser light as part of an energy production process. The use of lasers today is widespread in industrial, scientific and engineering applications. However, for ICF a major drawback to large-scale adoption may have been the cost and time to field a decisive demonstration of ICF itself, as well as the lack of a clear path to an economically attractive commercial realization for an energy production cycle.
In “Optical Configurations for Fusion Laser,” by R. O. Hunter, Jr., Aspen, Colo., submitted Dec. 7, 2016, Patent No. 62/497,908, and incorporated by reference, and “Lookthrough Compression Arrangement,” by R. O. Hunter, Jr., Aspen, Colo., submitted Oct. 31, 2016, Patent No. 62/496,885, and incorporated by reference, Innoven has outlined new laser architectures and elements that may lead to such a cycle. This patent contains a description of another type of overall architecture that may further reduce the cost and complexity for this application. Even though formulated for ICF energy production, there are potentially many applications for the inventions described herein in other areas. “Optical Configurations for Fusion Laser,” supra, described how to take laser energy generated at a longer pulse length and relatively poor beam quality and then compress it in space and time to produce a high energy pulse (≳107 joules) in a short pulse length (˜10−9 seconds) to impinge over a small area (˜0.01-0.1 cm2) of an ICF target. Furthermore, it described how to do this at a reasonable efficiency.
The invented techniques enable the compression operation for the ICF application to occur in gaseous media and greatly reduced (near damage levels) the required area of material surfaces. This may result in laser systems with a 102:1, or greater, reduction in precision optical element area for a given energy compared to existing technology, such as exemplified in the National Ignition Facility (NIF) (see “The National Ignition Facility: Laser System, Beam Line Design and Construction,” by R. H. Sawicki, in M. A. Lane and C. R. Wuest (Eds.), Optical Engineering at the Lawrence Livermore National Laboratory II: The National Ignition Facility, Proceedings of SPIE, Vol. 5341, 2004, pp. 43-53, incorporated by reference herein for all purposes). Overall, the cost per unit of energy for the architecture and elements may be over 102-103 lower than such existing technology. In addition, the reduction in optical element number, size, and precision permits rapid demonstration and deployment of the technology. Herein, further reduction in complexity and cost from the architecture shown in “Optical Configurations for Fusion Laser,” supra, may be realized by more compact packaging and reduction in number of separate beam paths to produce such compression and optical quality improvement.
“Lookthrough Compression Arrangement,” supra, details how an optical arrangement with very high optical gain for the input seed extraction pulse, amplified by converting the energy from a pump pulse, may be realized while having an output pulse length shorter than the pump pulse and of better optical quality. To avoid optical damage, the extraction pulse output, increased by the optical gain relative to the input optical fluence is then transmitted to the target without impinging on material optical elements. Considering the assembly for the extraction pulse and pump pulse interacting in scattering medium to be described as a stage, a single or multi-section stage arrangement with different gaseous media and/or optical scattering properties is described that enables very high gains of the extraction pulse output relative to its seed input. Gains of 103-104 for particular applications and arrangements then may be realized, resulting in large reduction of costs relative to glass laser technology. In “Lookthrough Compression Arrangement,” supra, each separate channel of the Fast Compressor stage may be isolated from adjacent channels and may be driven by an associated pump pulse element, that may be compressed from the Primary Laser Source, such as that described in “Optical Configurations for Fusion Laser,” supra.
A copending patent application “Optical Configurations for Fusion Laser,” supra, described a general laser architecture that had a Primary Laser Source followed by a Compression Section and a Vacuum Transition that was directed towards irradiation of an Inertial Confinement Fusion (ICF) Target. This copending application described a method of forming the Compression Section that entailed an optically multiplexed Raman Aperture Combiner that addressed a multichannel array of Active Time Delay Mirrors (ATDMs) resulting in a large temporal compression ratio whose output then pumps a Fast Compressor.
There is a need for architecture and elements that may permit the temporal and spatial compression of low cost energy for the ICF application, leading to compression costs on the order of $1-$10/joule, a major improvement over the approximate $103/joule costs exemplified in NIF. Coupled with low cost Primary Laser Source energy generation, a cost reduction of over 102:1 may be desired, thereby leading to economics suitable for both ICF technology demonstration (target ignition) and commercial energy production.